Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$233.72	12.721%	$263.4515	$263.45	$263.45	$263.50
Purchase #2	$162.97	4.272%	$169.9321	$169.93	$169.95	$169.90
Purchase #3	$160.41	7.466%	$172.3862	$172.39	$172.40	$172.40
Purchase #4	$213.75	9.672%	$234.4239	$234.42	$234.40	$234.40
Purchase #5	$238.31	7.186%	$255.435	$255.44	$255.45	$255.40
Purchase #6	$242.43	11.405%	$270.0791	$270.08	$270.10	$270.10
Purchase #7	$103.86	13.515%	$117.8967	$117.90	$117.90	$117.90
7 purchase totals =	$1,355.45		$1,483.6045	$1,483.61	$1,483.65	$1,483.60